This is a node group that adds puddles to a material.
Use a separate mapping node for the textures and the puddles, as the puddles has a small normal map for slight ripples. Get the normal map size right with the mapping node before changing the puddle scale (set the texture coordinate to object).
It already contains a Normal Map node so you can just plug in the texture on is own.
It uses Blender Guru's PBR shader to compile the PBR maps - (https://www.blenderguru.com/tutorials/pbr-shader-tutorial-pt1/)
The file contains textures from CG textures - (http://www.textures.com/) and Poliigon -(https://www.poliigon.com/home). (That's why the files so big).